This present invention relates generally to a method and device for manufacturing printer ribbons formed in a continuous loop within a cartridge. More specifically, the invention relates to a method and device for joining the two ends of a ribbon to form it into a continuous loop, by providing for durable overlap-welding by means of ultrasonics.
Methods and devices for ultrasonic welding of printing ribbons are known whereby a joint is produced by overlapping the ends of the ribbon cross-wise, and then welding the ends as taught in U.S. Pat. No. 3,821,048 to Acker and U.S. Pat. No. 4,629,530 to Becking. In practice, this type of welding of the ends of the ribbon has proved disadvantageous with respect to the structure of the ribbon ends and the life of the ribbon. The joint or weld thus produced has proven weak and has also been found to interfere with print quality when the printer strikes the joint in the ribbon. Ribbons joined by this method have proven particularly troublesome as the number of pins employed on the print heads of modern dot matrix printers has increased to 24 and even 48 wires. This increase in wires increases the stress on the joint. Further, the increase in number of wires has corresponded to a decrease in their thickness, and the thinner wires can be damaged by repeatedly striking the joint. Multicolor ribbons may also not be welded in accordance with Acker or Becking because the colors become blurred in the areas at the joint. Further, the welding devices of both Acker and Becking necessitate a multitude of specially manufactured, costly mechanical and pneumatic components and are accordingly time and labor-intensive in maintenance.
U.S. Pat. No. 4,018,955 issued to Klauke discloses a method of achieving colorabsorbing joints. Klauke teaches welding the overlapped printing ribbons by laying a metal grid above the weld under a sonotrode, and laying another under the weld on the anvil to produce a weld with ink-bearing cells which is suitable for single-color or multi-color continuous printer ribbon.
In one aspect, an object of the invention is to create a method and a device which will provide for automated joining of ends of ribbons by means of durable overlap welding in a manner which is more durable and interferes less with printer quality and permits precise welding of multi-color ribbons. In a second aspect, an object of the invention is to invent a device for carrying out the method which utilizes, to a large extent, commercial standard parts and appliances which are correspondingly simple and inexpensive to maintain. In a third aspect, an object of the invention is to provide an improved means for retaining the ribbon ends in precise alignment while being cut and joined. In a fourth aspect, an object of the invention is to provide a quicker and more convenient means for removing the waste ends of ribbons left after the cutting process. In a fifth aspect, an object of the invention is to provide a means for producing a weld of a length and strength suitable for the size and type of ribbon being joined.